Electronic devices and other devices often produce heat during operation that needs to be dissipated away from the device. Heat sinks are often used for this purpose; a heat sink is a passive component that cools a device by dissipating heat into the surrounding environment. In order for the heat sink to operate properly, the heat from the device must be transferred to the heat sink over a thermal connection. While the term heat sink is used herein it should be understood that the term refers to all types of heat dissipating devices, including heat pipe modules and thermal ground planes.
A common arrangement for electronic devices is a plurality of electronic components attached to a printed circuit board (PCB). Heat from these multiple components is transferred to one or more heat sinks using thermal connections. Each component on the PCB is a particular distance from the heat sink (tolerance) and the heat must be effectively transferred across the tolerance from the component to the heat sink. Accordingly, the tolerance is often filled with a thermal connector, such as a heat spreader and/or thermal interface material.
When a single heat sink serves multiple components, the thermal connectors often must accommodate several different tolerances. Some of the proposed solutions for this issue include the use of thermal pastes, thermal greases, and thermally conductive pads that are compressible and expandable. These thermal connectors typically have fairly low thermal conductivities, in the range of 3 watts per meter kelvin (W/mK). Some thermal pads have conductivity as high as 17 W/mK but they can only be compressed to 10%-20% between the heat sink and the component or the component will be damaged. This limits the size of the starting gap between the component and the heat sink and makes it more difficult to assemble the device.
Accordingly, there is a need for better thermal connectors to transfer heat between heat generating components and heat sinks. More particularly, there is a need for thermal connectors that accommodate a variety of tolerances between multiple components of a heat generating device and a heat sink.